The SMART team created a reference implementation of the draft FHIR Bulk Match Operation, with source code publicly available at https://github.com/smart-on-fhir/bulk-match-client and https://github.com/smart-on-fhir/bulk-match-provider.
More information is also available on the HL7 FHIR Foundry entries for the Client and the Server
Below is a recording of a community demonstration of the reference implementation held on Sept 6, 2024.